1. Field of the Invention
This invention lies in the field of study of the human eye. More particularly it concerns a process of determining the physiological condition of the retina of the eye, and of measuring the field of vision of the eye, by entirely objective automatic means irrespective of arbitrary eye movements of the patient.
2. Description of the Prior Art
In the prior art, ophthalmologists have routinely made measurements on the eyes of patients, such as determining the visual field by seating a patient before a blackened board and have a test person move a small whitened sphere along radial lines from the outer extreme of the board toward the central portion, in such a manner that the patient responds when he sees the spot, being cautioned to maintain the eye constantly fixed along the axis of the board. In other cases, semi-automatic stimulators have been used in which a plurality of small lamps are positioned at selected locations on a board or hemisphere. These lights are illuminated momentarily in selected succession and the patient indicates by closing a switch or pressing a button that he does or does not see the spot of light.
Also in the study of the visual process, research personnel have made measurements of the potential generated by the retina in response to a visual stimulus. These measurements have been made at various positions on the face and forehead of the patient by means of thin metal electrodes which are attached to the skin surface.
There are two particular types of potentials which are measured, namely, the electro-retinal potential and the visual evoked response.
These and other measurements can be made on the apparatus of this invention by the use of suitably placed electrodes, as are well known in the art.